1. Field of the Invention
This invention relates to security systems and, more particularly, to a component of a security system that can be attached to an article to facilitate monitoring thereof so as to detect unauthorized removal of the article.
2. Background Art
Many retail establishments display merchandise in such a manner that prospective purchasers are allowed to pick articles up and manipulate them as they would in normal use, for purposes of inspection and testing. For example, electronics stores commonly display large quantifies of cellular phones, camcorders, radios, etc. in this manner. Security systems are necessary to prevent unauthorized removal of these products from the display areas.
Ideally, such security systems afford the prospective customer the freedom to pick up, inspect, and in certain cases operate the article without substantial interference from the system. These systems are at the same time designed to limit, within a prescribed range, the distance the prospective purchaser can transport the article from the display.
It is known to use purely mechanical systems, such as cables, to accomplish the above end. In certain environments, these mechanical systems are easily defeated, as by cutting or breaking loose the cable anchor. With such systems, the store operator is given no sensory indication that the system has been defeated.
Electronic systems, such as shown in U.S. Pat. No. 5,172,098, afford a more sophisticated monitoring tool to the store owner. The system in U.S. Pat. No. 5,172,098 utilizes a separate sensor for each article to be monitored. The system is armed by attaching each of the active sensors to an article to be monitored. A double-sided, adhesive pad is attached to a surface on the sensor housing from which an actuating switch button projects and a mounting surface on an article. With this arrangement, the button is captive between the sensor housing and article in a depressed state to close a monitoring circuit. If the circuit is broken, either by prying loose the sensor from the article or severing a cord communicating between a sensor and a control unit, an alarm sounds. LED's on splitter boxes, remote from the articles and on the sensors, allow the store owner to trace the article that has been tampered with.
The above system has been highly commercially successful. For this system to operate effectively, it is critical that the sensor housing be positively secured to the article to be monitored with the actuating button depressed to arm the system. Currently available adhesives are tenacious enough to maintain the sensors positively against a flat surface on the articles.
However, a large number of consumers products do not have a flat surface that lends itself to the positive mounting of the sensor housing. Many consumer products are of late being designed with curved contours to produce a streamlined appearance. For example, hand held camcorders and cellular phones often have a rounded shape that facilitates comfortable grasping thereof as well as produces a "high tech" look. This type of product may be totally lacking a flat surface with an area substantial enough to accommodate the confronting face on the sensor housing.
In the event that the article to be monitored does not have a suitable flat surface for attachment of the sensor housing, two conditions commonly occur. In the event that the sensor is attached to a convex surface, less than the entire exposed surface on the adhesive pad on the sensor housing makes facial contact with the surface on the article. The sensor housing then has a contact area that is less than what was contemplated in the original design to assure a positive bond between the sensor housing and article. The adhesive pad on the flat contacting surface of the sensor may not have a sufficient contact area on the article to produce an effective bond. The sensor may then be relatively easily shifted, as by a rocking motion, on the article. The sensor is in this condition prone to breaking free of the article.
Even if a relatively substantial contact area is established between the adhesive pad and the convex article surface, there may remain a gap between the sensor housing and article surface at one or more edges of the housing. This facilitates prying loose of the sensor housing by a thief.
On some articles, the most accessible surface on which the sensor can be placed has a concave shape. When the sensor is applied, it may bridge two points on the surface. This results in less than full contact between the sensor housing mounting surface and the article. Accordingly, the strength of the bond is compromised.
Further, the actuating button may be less than fully depressed with the sensor housing operatively connected to the article in this state. The result may be that a slight shifting of the sensor housing on the article may break the circuit so as to produce an alarm, when in fact there has been no security breach.
It is impractical to custom shape sensors to individual articles, and thus those in the art have merely contended with the above problems.